The present invention relates to a device for detecting and/or adjusting the position of two bodies capable of being moved relative to each other, the bodies having cross gratings. The invention is thus a measuring device allowing the detection of the six possible motion components taking place during a primarily plane, two-dimensional translatory relative motion of two bodies.
In known position measuring devices, it is generally not possible to detect all six possible motion components. In addition, reference bodies used as measurement standards, having two or three plane reference surfaces precisely arranged relative to each other, are required to perform the measurement.
The known devices are not only restricted with regard to the detection of motion components, but moreover have an extraordinary degree of structural complexity. Generally, they are based on the use of a linear measurement standard.
The object of the present invention is to provide a device which, using a simple design, allows to detect all six motion components.
In one aspect, the invention is a device for detecting and adjusting a position of two bodies movable relative to each other, comprising a plane areal measurement standard disposed on a first of the bodies as a plane reference surface, comprising a two-dimensional grating division, a plane surface disposed on a second of the bodies, the plane surface being parallel to the measurement standard and having at least two gratings arranged on the plane surface forming a scanning head and at least one distance measuring device disposed between the first and second bodies.
In another aspect, the invention is a device for positioning a wafer carrier body of a wafer stepper machine, comprising a plane areal measurement standard disposed on a base portion of the machine as a plane reference surface, comprising a two-dimensional grating division, a plane surface disposed on a carrier body, the plane surface being parallel to the measurement standard and having at least two gratings arranged on the plane surface forming a scanning head, and at least one distance measuring device disposed between the base portion and the carrier body. The device also includes contact free bearings and actuators provided on the component carrier body, and a controller for receiving position data from the scanning head and the at least one distance measuring device, wherein the orientation of the component carrier body relative to the two-dimensional grating division is adjustable by controlling the bearings and actuators with the controller, in response to the position data.
According to the present invention, relative translations and a rotations can be detected by optical means and, at the same time, the distances at three locations between two surfaces of the bodies can be detected, so that all six components of the relative motion of the bodies are detected.
With the known technology, it was necessary to manufacture measurement standards, such as reference bodies, having two to three plane reference surfaces precisely arranged relative to each other. According to the invention, it is only required to make one surface, which constitutes a considerably lower production effort. Compared to this, the use of cuboidal measuring standards having two or more reference surfaces requires a considerably greater technical effort in carrying out measurements.
According to the present invention, an exact spatial alignment of the components is not required, and the parallelism of the measuring system components relative to two planes does not have to be guaranteed to carry out the measurement. In the present invention, two bodies are to be arranged roughly parallel to each other relative to only one plane, which is additionally facilitated by the distance-measuring devices resulting in three identical distances that equal to both planes being parallel. A jointing operation, as was required in previous cases, is not required, thus making it considerably easier for measurements to be carried out.
Using incremental position-measuring systems having grating divisions for position and situation measuring results in a high accuracy, high resolution measurement, low susceptibility to failure (electromagnetic), stability with regard to atmospheric influences such as air temperature, humidity, and pressure that can have a disruptive effect when using laser interferometers.